Just reading a book is not enough. One has to understand the concepts and then practice them in games.
i am a retired college professor. The rule of thumb for college classes is that every hour of lecture should be followed by three hours of work outside class. Students read, do exercises, complete projects, and otherwise think about the material.
i think too many chess.com players think that playing blitz, reading a book, or watching a video is enough to advance. No. One has to do additional work. Try first to understand the lesson. Then look for opportunities to implement the lesson. And then review your games, to see how the lesson should have been applied.
Maybe You STUPID?! DUR!